Most electric vehicles will not take you farther than 100 miles on one charge, and while that works for going around town, energy drains quickly.
To boost their range more toward 300 miles or more, researchers are working on a battery that “breathes.” This battery has the potential to one day replace the lithium-ion technology of today’s EVs, said researchers at Mie University in Japan.
“Lithium-air batteries are lightweight and deliver a large amount of electric energy,” said Nobuyuki Imanishi, Ph.D. “Many people expect them to one day be used in electric vehicles.”
The main difference between lithium-ion and lithium-air batteries is the “air” version replaces the traditional cathode — a key battery component involved in the flow of electric current — with air. That makes the rechargeable metal-air battery lighter with the potential to pack in more energy than its commercial counterpart.
While lithium-air batteries are an exciting technology to watch, they still have some kinks that need ironing out. Researchers are forging ahead on multiple fronts to get the batteries in top form before they debut under the hood.
One of the main components researchers are working on is the batteries’ electrolytes, materials that conduct electricity between the electrodes. There are currently four electrolyte designs, one of which involves water. The advantage of this “aqueous” design over the others is it protects the lithium from interacting with gases in the atmosphere and enables fast reactions at the air electrode. The downside is that water in direct contact with lithium can damage it.
Seeing the potential of the aqueous version of the lithium-air battery, Imanishi’s team went to work. Adding a protective material to the lithium metal is one approach, but this typically decreases the battery power. So they developed a layered approach, sandwiching a polymer electrolyte with high conductivity and a solid electrolyte in between the lithium electrode and the watery solution. The result was a unit with the potential to pack almost twice the energy storage capacity, as measured in Watt hours per kilogram (Wh/kg), as a lithium-ion battery.
“Our system’s practical energy density is more than 300 Wh/kg,” Imanishi said. “That’s in contrast to the energy density of a commercial lithium-ion battery, which is far lower, only around 150 Wh/kg.”
The battery shows promise, with high conductivity of lithium ions, and the ability to discharge and recharge 100 times. In addition to powering EVs, lithium-air batteries could one day have applications in the home, thanks to their low cost. Power output remains a big hurdle, but Imanishi said his group will hone this approach, as well as exploring other options, until lithium-air becomes a commercial reality.